JP2016062804A - Luminaire and display device using wavelength conversion sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength conversion sheet used in a luminaire and a display device, which attains both barrier property and wavelength conversion efficiency, and can emit even color light regardless of a lens sheet to be used by reducing a scattering property of light incident to the wavelength conversion sheet.SOLUTION: A wavelength conversion sheet has an optical adjustment layer having a predetermined reflection rate according to a light-emitting characteristic of a light source and a light-emitting characteristic of a light source, as a barrier layer provided on the light incident surface and light emission surface of the wavelength conversion sheet; and thereby converts light emitted from the light source into light having a different wavelength characteristic with high efficiency. Namely, provided is a wavelength conversion sheet having barrier property, a small amount of light-emitting material and thin thickness.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an illumination device using a wavelength conversion sheet and a display device.

  In recent flat panel displays and the like typified by a liquid crystal television, a direct type illumination device and an edge light illumination device are mainly used. In the direct type illumination device, a plurality of LEDs (Light Emitting Diodes) are regularly arranged on the back surface of the panel as light sources. Between the image display element such as a liquid crystal panel and the light source, a diffuser plate having a strong light scattering property is used so that the LED as the light source is not visually recognized.

  On the other hand, in an edge light type illumination device, a plurality of LEDs are arranged on an end surface (incident surface) of a light-transmitting plate called a light guide plate. Generally, light deflection that efficiently guides light incident from the end face of the light guide plate to the exit surface on the surface (light deflection surface) opposite to the light exit surface of the light guide plate (surface facing the image display element). An element is formed. Currently, the light deflection element formed on the light deflection surface is generally printed with white ink in the form of dots (see, for example, Patent Document 1).

  In recent years, a method of displaying white using RGB three-color LEDs has been attracting attention with the aim of achieving higher definition and wider color gamut of liquid crystal displays. However, in the method of performing white display by simultaneously turning on and mixing the LED light sources of three colors of RGB, in order to obtain a sufficiently mixed and uniform white, the direct type method requires a thick diffuser, and the edge In the light type, it is necessary to maintain a long light guide distance, and it is difficult to reduce the size and thickness of the display. Therefore, a method for displaying white color by combining a blue LED light source and a phosphor has been proposed. This method includes a method of sealing a blue LED chip with a phosphor resin, and a method of arranging a phosphor sheet separately from the blue LED and causing surface emission (see, for example, Patent Documents 2 and 3).

  One of the methods using a blue LED light source and a phosphor uses a quantum dot. A quantum dot is a luminescent semiconductor nanoparticle, the range of a diameter is about 1-20 nm, a wide excitation spectrum is shown, and quantum efficiency is high. Furthermore, there is an advantage that the wavelength of light emission can be completely adjusted over the entire visible range only by changing the dot size or the type of semiconductor material. As such, quantum dots have the potential to create virtually any color, especially the warm white that is highly desired in the lighting industry. In addition, it is possible to obtain white light having different color rendering index by combining three types of dots corresponding to red, green, and blue emission wavelengths.

In an illumination device using quantum dots, the wavelength conversion layer that converts the blue light wavelength to another wavelength is used by sealing it with a barrier film or a laminate thereof to increase the life.
The barrier film is a protective film in which a thin film is formed by vapor deposition or the like on the surface of a base material such as a plastic film in order to prevent permeation of moisture contained in a gas such as oxygen or air.

JP-A-1-241590 JP 2010-170961 A JP 2010-225373 A

However, in the wavelength conversion sheet according to the methods of Documents 2 and 3, a scattering agent is dispersed in the wavelength conversion sheet in order to disperse the phosphors uniformly. However, since the incident light is also scattered by the scattering agent, the front luminance of the display is lowered. In order to improve the front luminance of the liquid crystal display, a diffusion film or a lens sheet must be disposed on the light exit surface side of the wavelength conversion sheet. However, the light incident on the lens sheet includes light that travels in the front direction due to reflection at the lens surface and the air interface, and light that is returned to the wavelength conversion sheet as reflected light. For this reason, the light returned by the lens sheet passes through the wavelength conversion sheet again, so that fluorescence is emitted. Since the amount of light returned by the lens sheet varies depending on the lens shape, there arises a problem that the color of light emitted to the front of the display varies depending on the lens sheet disposed on the wavelength conversion sheet.
In addition, when the wavelength conversion sheet is disposed on the exit surface side of the lens sheet, the light is scattered by the scattering agent dispersed in the wavelength conversion sheet as described above. Since the reflected light does not pass through the wavelength conversion sheet, the amount of fluorescence emission decreases. In order to achieve sufficient color conversion efficiency, the phosphor layer must be thickened.

  The present invention has been made in view of the problems as described above, and achieves both the barrier property of the barrier film and the improvement of the color conversion efficiency of the wavelength conversion sheet, and the position and shape of the lens sheet used. It is an object of the present invention to provide a wavelength conversion sheet capable of emitting uniform color light regardless of the above.

As means for achieving the above object, the invention according to claim 1 provides:
A wavelength conversion sheet having a wavelength conversion layer and a light incident surface and a light emission surface arranged to face each other with a positional relationship sandwiching the wavelength conversion layer, wherein the wavelength conversion layer converts the wavelength of incident light into a long wavelength Containing at least one or more kinds of light emitting materials to be converted to the side, and the light incident surface includes a first base material layer formed on the wavelength conversion layer side and at least a first base material layer on the first base material layer A first functional layer on which one optical adjustment layer is laminated, wherein the first optical adjustment layer has a layer made of at least silicon oxide or aluminum oxide, and the first optical adjustment layer includes the first optical adjustment layer. The spectral reflectance on the surface opposite to the first base material layer is a wavelength conversion sheet characterized in that the minimum value is 0.5% or more and 10% or less in the wavelength region of 300 nm to 500 nm. is there.

As means for achieving the above object, the invention according to claim 2 provides:
A wavelength conversion sheet having a wavelength conversion layer and a light incident surface and a light emission surface arranged to face each other with a positional relationship sandwiching the wavelength conversion layer, wherein the wavelength conversion layer converts the wavelength of incident light into a long wavelength Containing at least one kind of light emitting material to be converted to the side, the light emitting surface has a second base material layer formed on the wavelength conversion layer side, and at least a first base material layer on the second base material layer A second functional layer in which two optical adjustment layers are laminated, and the second optical adjustment layer has a layer made of at least silicon oxide or aluminum oxide, and has a wavelength region of 500 nm or more and 680 nm or less. The wavelength conversion sheet is characterized in that the maximum value of the spectral reflectance in the wavelength range of 300 nm to 500 nm is higher than the minimum value of the spectral reflectance in the range.

As means for achieving the above object, the invention according to claim 3 is:
The refractive index difference between the translucent resin constituting the wavelength conversion layer and the dispersed particles contained in the translucent resin is 0.1 or less, according to claim 1 or 2. It is a wavelength conversion sheet.
As means for achieving the above object, the invention according to claim 4 provides:
The first optical adjustment layer and the second optical adjustment layer are different from adjacent layers among any one of an inorganic substance, an organic substance, and a mixture of an inorganic substance and an organic substance in addition to the silicon oxide layer or the aluminum oxide layer. The wavelength conversion sheet according to any one of claims 1 to 3, wherein a layer having a refractive index is laminated.

As means for achieving the above object, the invention according to claim 5 provides:
It is an illuminating device using the wavelength conversion sheet of any one of Claim 1 thru | or 4, Comprising: The light inject | emitted from the said light source injects from the said light-incidence surface side of the said wavelength conversion sheet | seat. It is an illuminating device.
As means for achieving the above object, the invention according to claim 6 provides:
6. The illumination device according to claim 5, wherein a light source having a maximum emission wavelength in a wavelength range of 300 nm to 500 nm is used.

As means for achieving the above object, the invention according to claim 7 provides:
The illumination device according to claim 5 or 6, wherein the wavelength width of the light emission distribution when the maximum value of the light emission intensity of the light emitted from the light source is halved is in the range of 10 nm to 60 nm.
As means for achieving the above object, the invention according to claim 8 provides:
A display device comprising the illumination device according to claim 5, wherein a display panel and a color filter for displaying an image are arranged on an observer side of the wavelength conversion sheet. It is.
As means for achieving the above object, the invention according to claim 9 provides:
9. The display device according to claim 8, wherein an optical sheet on which either a prism shape or a microlens shape is formed is laminated on a light exit surface side of the wavelength conversion sheet.

  According to the wavelength conversion sheet of the present invention, at least one of the light incident surface and the light emission surface of the wavelength conversion sheet has a predetermined reflectance designed in consideration of the light emission characteristics of the light source and the light emission characteristics of the light emitting material. By forming such an optical adjustment layer, both barrier properties and light emitted from the light source can be converted into light having different wavelength characteristics with high efficiency. Therefore, since the barrier layer and the optical adjustment layer can be integrated, the display can be reduced in size and thickness, and the manufacturing process can be simplified.

It is typical sectional drawing which shows the structure of the display apparatus of embodiment of this invention. It is an enlarged view of the wavelength conversion sheet of the embodiment of the present invention. It is a figure which shows an example of the light emission characteristic of the light source of embodiment of this invention. It is a figure which shows an example of the light emission characteristic of the wavelength conversion sheet of embodiment of this invention. It is a figure which shows an example of the light emission characteristic of the light source of embodiment of this invention. It is a figure which shows an example of the light emission characteristic of the light source of embodiment of this invention. It is a figure which shows an example of the light emission characteristic of the wavelength conversion sheet of embodiment of this invention. (A) It is typical sectional drawing which shows the structure of the optical adjustment layer of embodiment of this invention. (B) It is a reflectance characteristic figure of the optical adjustment layer of embodiment of this invention. (A) It is typical sectional drawing which shows the structure of the optical adjustment layer of embodiment of this invention. (B) It is a reflectance characteristic figure of the optical adjustment layer of embodiment of this invention. (A) It is a light emission characteristic figure of the illuminating device of embodiment of this invention. (B) It is a light emission characteristic figure of the illuminating device of the comparative example of this invention. (A) It is typical sectional drawing which shows the structure of the optical adjustment layer of embodiment of this invention. (B) It is a reflectance characteristic figure of the optical adjustment layer of embodiment of this invention. (A) It is typical sectional drawing which shows the structure of the optical adjustment layer of embodiment of this invention. (B) It is a reflectance characteristic figure of the optical adjustment layer of embodiment of this invention. (A) It is typical sectional drawing which shows the structure of the optical adjustment layer of embodiment of this invention. (B) It is a reflectance characteristic figure of the optical adjustment layer of embodiment of this invention. (A) It is typical sectional drawing which shows the structure of the optical adjustment layer of embodiment of this invention. (B) It is a reflectance characteristic figure of the optical adjustment layer of embodiment of this invention. (A) It is typical sectional drawing which shows the structure of the optical adjustment layer of embodiment of this invention. (B) It is a reflectance characteristic figure of the optical adjustment layer of embodiment of this invention. (A) It is typical sectional drawing which shows the structure of the optical adjustment layer of embodiment of this invention. (B) It is a reflectance characteristic figure of the optical adjustment layer of embodiment of this invention. (A) It is a viewing angle characteristic view of the illuminating device of embodiment of this invention. (B) It is a viewing angle characteristic view of the illuminating device of the comparative example of this invention. It is typical sectional drawing which shows the structure of the display apparatus of another embodiment of this invention. It is typical sectional drawing which shows the structure of the display apparatus of another embodiment of this invention. In addition, since each drawing is a schematic diagram, dimensions, shapes, numbers, and the like are exaggerated and omitted.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

First, the function and effect of this embodiment will be described.
As shown in FIG. 1, the liquid crystal display device 1 (display device) according to the present embodiment includes an image display element 2 and an illumination device 3 arranged facing the light incident side of the image display element 2. FIG. 2 is an enlarged view of the wavelength conversion sheet 4 in FIG.

In the present embodiment, by appropriately setting the film thickness of the optical adjustment layers 13a and 13b and the material to be laminated, the light emission characteristics of the light source 6 and the light emission characteristics of the light emitting material are provided while providing barrier properties to the functional layers 8a and 8b. Reflective characteristics designed to take a predetermined reflectance into consideration.
Hereinafter, the characteristics and effects of the wavelength conversion sheet when a light source having a maximum emission wavelength in the range of 300 nm to 500 nm in the blue light wavelength band is used as the light source 6 will be described. The spectral reflectance in the following description is defined as the spectral reflectance on the surface of the functional layer 8 on the side opposite to the wavelength conversion layer 15.

(Functional layer (light incident side))
First, the reflection characteristics and operational effects of the functional layer 8a on the light incident surface side from the light source 6 will be described.
The light emitted from the light source 6 is deflected in the front direction by the light deflection element 18 provided in the light guide 7 and is collected by the light collecting sheet 20. The light emitted from the light collecting sheet 20 is diffused by the diffusion sheet 28 and then enters the wavelength conversion sheet 4 from the functional layer 8a side.

  The functional layer 8a includes a member used so that the minimum value of the spectral reflectance is 0.5% or more and 10% or less in a range of 300 nm to 500 nm which is a wavelength region in which the light source 6 has a maximum emission wavelength. Determine the film thickness. Further, the spectral reflectance in the wavelength region of 500 nm or more and 680 nm or less is set to be higher than the spectral reflectance at 500 nm or less. That is, the reflectance in the vicinity of 450 nm of blue light incident from the light source 6 is set higher in the vicinity of 550 nm of green light and 600 nm of red light.

With the above setting, the blue light emitted from the light source 6 is transmitted through the functional layer 8 a in a band of 500 nm or less due to low reflectance, and is incident on the wavelength conversion layer 15. Here, when blue light is incident on the light emitting material 15a in the wavelength conversion layer 15, the wavelength is converted to the long wavelength side. At this time, various factors on the incident surface side and the emission surface side centering on the light emitting material 15a. Light is emitted in any direction.
Here, when the functional layer 8a does not have the reflection characteristics of the present embodiment, the light emitted toward the light incident surface side of the wavelength conversion sheet 4 loses light due to absorption of the lower layer, so it is efficient. It becomes difficult to advance light to the visual side.
However, in this embodiment, since the functional layer 8a has a high reflectance on the long wavelength side, light directed toward the light incident surface side can be reflected. As a result, the traveling direction of light is deflected in the direction of the light exit surface, and the light can be emitted from the exit surface side of the wavelength conversion sheet 4. That is, it has the effect of increasing luminous efficiency. In the present invention, the functional layer 8a or a part of the functional layer 8a is a layer made of silicon oxide or aluminum oxide, so that the light emission characteristics of the light emitting layer can be prevented from deteriorating.

(Functional layer (light emission side))
Next, the reflection characteristics and functions and effects of the functional layer 8b on the light emission surface side from the light source 6 will be described.
Contrary to the functional layer 8a described above, the functional layer 8b is a member that is used so that the minimum value of the spectral reflectance is 0.5% or more and 10% or less in the wavelength region of 500 nm or more and 680 nm or less, and the film thickness thereof. To decide. Further, the spectral reflectance in the wavelength range of 300 nm to 500 nm is set to be higher than the spectral reflectance in the range of 500 nm or more (long wavelength side). That is, the reflectance in the vicinity of 450 nm of blue light incident from the light source 6 is set higher than the reflectance in the vicinity of green light 550 nm and red light 600 nm.

With the above settings, the light converted to the long wavelength side by the wavelength conversion layer 15 is transmitted because the long wavelength side of the functional layer 8b has a low reflectance, and can be emitted from the emission surface side of the wavelength conversion sheet 4. it can.
Here, when the functional layer 8b does not have the reflection characteristics of the present embodiment, the light (blue wavelength light) that has not been converted by the wavelength conversion layer 15 and has reached the functional layer 8b is emitted from the emission surface side without being converted. Therefore, the wavelength conversion efficiency is lowered.
However, in the present embodiment, since the functional layer 8b has a high reflectance characteristic on the short wavelength side, light that reaches the functional layer 8b without being converted is reflected and is incident on the wavelength conversion layer 15 again. As a result, there is an effect that the probability of emitting light by being converted to the long wavelength side by the light emitting material 15a is increased, and the light emission conversion efficiency is improved. In the present invention, the functional layer 8a or a part of the functional layer 8a is a layer made of silicon oxide or aluminum oxide, so that the light emission characteristics of the light emitting layer can be prevented from deteriorating.

  Although the conversion efficiency is increased even if the functional layers 8a and 8b are used alone, they are formed on both the light incident side and the emission side of the wavelength conversion sheet 4 so that the wavelength conversion layer 15 is sandwiched between them. The conversion efficiency can be further improved.

  In the above description, the case where the light source having the maximum emission wavelength in the wavelength range of 300 nm or more and 500 nm or less has been described. However, the present invention is not limited to this. What is necessary is just to set a characteristic suitably.

  In the above, the function and the characteristic action effect of this embodiment were demonstrated. Below, the detail of a structure of each layer in this embodiment is demonstrated.

(Image display element)
The image display element 2 is configured by sandwiching a liquid crystal layer 9 between two polarizing plates 10 and 11.
The image display element 2 is preferably an element that transmits and blocks light in pixel units and displays an image, and more preferably a liquid crystal display element. A liquid crystal display element is a typical element that transmits / shields light in pixel units and displays an image, and can improve image quality and reduce manufacturing cost compared to other display elements. Can do.

(Lighting device)
The illuminating device 3 is disposed on the side surface of the light guide 7 and the laminated body 21 in which the wavelength conversion sheet 4, the diffusion sheet 28, the light collection sheet 20, and the light guide 7 are arranged in this order from the image display element 2. The light source 6 is configured to include at least the light guide 7 and the reflection plate 5 (reflection member) surrounding the light source 6.
The illuminating device 3 is disposed with the wavelength conversion sheet 4 facing the image display element 2.

(reflector)
The reflecting plate 5 (reflecting member) reflects light leaking from the light guide 7 to the light guide 7 side. For example, a reflective sheet such as a white polyethylene terephthalate film, a metal vapor-deposited sheet, and many dielectrics are laminated. It is comprised by the reflective sheet etc. which were made.

(light source)
The light source 6 supplies light emitted from the light guide 7 toward the wavelength conversion sheet 4 from the side surface of the light guide 7, and a point-like, linear, or planar light source may be employed. it can.
Examples of light sources suitable as the light source 6 include, for example, LEDs and lasers. Examples of the types of LEDs and lasers include white, red, green, blue, and ultraviolet LEDs and lasers. In particular, it is desirable that the wavelength of the light source has a maximum emission wavelength in a region of 300 nm or more and 500 nm or less because it easily fits in the visible light region even after conversion by the wavelength conversion sheet 4.
In addition, it is desirable that the wavelength width of the light emission distribution when the maximum value of the light emission intensity of the light source is halved is in the range of 10 nm to 60 nm. More preferably, it is in the range of 10 nm to 50 nm, still more preferably in the range of 10 nm to 40 nm, and still more preferably in the range of 10 nm to 30 nm.
The light source 6 employs a point light source in which a plurality of light sources are spaced apart in the vicinity of the light incident surface of the light guide 7. As an example, the optical axis of each light source 6 is arranged in a direction substantially orthogonal to the light incident surface (including the case of orthogonality).

(Condensing sheet)
The condensing sheet 20 is a member having a function of condensing light transmitted through the light guide 7 in the visual direction, and for example, a prism sheet in which a plurality of prisms 24 are formed on the surface of the base material 23 is adopted. can do.

(Diffusion sheet)
The diffusion sheet 28 diffuses the light collected by the light collecting sheet 20 and protects the light collecting sheet 20, and the periodic structure formed on the light collecting sheet 20 and the periodic structure of the image display element 2. Has the function of reducing the occurrence of moiré.
As the diffusion sheet 28, for example, a sheet member in which an acrylic resin in which spherical particles are dispersed on a PET (polyethylene terephthalate) film can be employed.
Further, the diffusion sheet 28 may have a function of separating the polarization of the light collected by the light collecting sheet 20.
As the diffusion sheet 28 having such a polarization separation function, for example, reflective polarized light that transmits one polarized light and reflects the other polarized light as represented by DBEF (registered trademark) (manufactured by 3M). A separation sheet can be used.

(Wavelength conversion sheet)
For example, when blue light is emitted from the light source 6, the wavelength conversion sheet 4 is a member that is excited by the blue light and performs wavelength conversion so that, for example, green or red light can be extracted.
The wavelength conversion sheet 4 has a configuration in which the wavelength conversion layer 15 is sandwiched between a pair of functional layers 8.

(Wavelength conversion layer)
The wavelength conversion layer 15 converts a part of incident light into light having a longer wavelength, and the light emitting material 15a is dispersed and contained in the transparent resin 15c.

(Transparent resin)
Examples of the transparent resin 15c include, for example, an acrylic resin represented by PMMA (polymethyl methacrylate), PET (polyethylene terephthalate) resin, PC (polycarbonate) resin, COP (cycloolefin polymer) resin, PAN (polyacrylonitrile copolymer). And a transparent resin such as an AS (acrylonitrile styrene copolymer) resin.

(Luminescent material)
The light emitting material 15a may be any material that is excited by a light source and emits light at a different emission wavelength. For example, a fluorescent material or phosphorescent material made of a compound such as alkaline earth elements Ca, Sr, Ba, Sc, Y, La, Examples thereof include a phosphorescent material, CdSe, and quantum dots made of a group III-V element compound.
By using light storage as the light emitting material 15a, it is possible to provide an illuminating device that emits light for a certain period of time even after the LED is turned off. Further, by using quantum dots as the light emitting material 15a, an illumination device having a sharp emission wavelength peak can be obtained.

  Examples of the quantum dots include those in which a core as a light emitting portion is coated with a shell as a protective film. Examples of the core include cadmium selenide (CdSe), and examples of the shell include zinc sulfide (ZnS). Quantum efficiency is improved by covering surface defects of CdSe particles with ZnS having a large band gap. Further, the phosphor 3 may be one in which the core is double-coated with the first shell and the second shell. In this case, CsSe can be used for the core, zinc selenide (ZnSe) can be used for the first shell, and ZnS can be used for the second shell.

  The average particle diameter of the light emitting material 15a is preferably 1 nm to 20 nm.

  The content of the light emitting material 15a in the wavelength conversion layer 15 is preferably 1% by mass to 20% by mass, and more preferably 3% by mass to 10% by mass based on the total amount of the wavelength conversion layer 15. .

(Dispersed particles)
In the wavelength conversion layer 15, dispersed particles 15b may be dispersed in order to suppress aggregation of the light emitting material 15a. As the dispersed particles 15b, particles made of an inorganic oxide or particles made of a resin can be used. For example, the particles made of an inorganic oxide include particles made of silica, alumina or the like. The particles made of resin include acrylic particles, styrene particles, styrene acrylic particles and cross-linked products thereof, melamine-formalin condensate particles, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoro). Examples thereof include fluorine-containing polymer particles such as ethylene-hexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene-tetrafluoroethylene copolymer), and silicone resin particles. These particles may be used as a mixture of two or more.

  If the refractive index difference between the transparent resin 15c and the dispersed particles 15b in the transparent resin is large, light is scattered at the interface between the transparent resin 15c and the dispersed particles 15b. It will be scattered. For this reason, it is preferable that the refractive index difference between the transparent resin 15c and the dispersed particles 15b is small, and it is preferable that the refractive index difference between them is 0.1 or less. More preferably, it is 0.05 or less. More preferably, it is 0.01 or less. This is because if the refractive index difference is larger than 0.1, the scattered light increases and the light collecting effect is impaired.

  When incorporating the wavelength conversion sheet of the present embodiment into an illumination device, the wavelength conversion sheet can be disposed on the condensing sheet by suppressing scattered light from the transparent resin and the dispersed particles. Regardless of the type and number of light collecting sheets used in the above, a stable wavelength conversion effect can be exhibited.

  The average particle diameter of the dispersed particles 15b is desirably 1 μm or more and 100 μm or less. Preferably they are 1.0 micrometer or more and 50 micrometers or less. This is because when the particle size of the particles is smaller than 1 μm, it is difficult to sufficiently disperse the light emitting material 15a, and when the particle size is larger than 100 μm, the dispersed particles are too large and the dispersion state of the light emitting material 15a is lowered.

(Functional layer)
In the functional layer 8, the optical adjustment layer 13 is laminated on the substrate 12, and the surface of the substrate 12 on which the optical adjustment layer 13 is not formed is bonded to the wavelength conversion layer 15.

  The substrate 12 and the wavelength conversion layer 15 may be bonded together by an adhesive, and the adhesive layer is composed of, for example, a UV curable adhesive, a thermosetting adhesive, an adhesive, a hot melt agent, and the like, and has a water vapor barrier. It is desirable to have properties.

(Base material)
The substrate 12 is desirably made of a material having gas barrier properties and transparency, workability, heat resistance, and the like. Examples of such materials include thermoplastic resins such as polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polystyrene, polyethylene naphthalate, polyethersulfone, and cyclic amorphous polyolefin, and polyfunctional acrylates, polyfunctional polyolefins, and unsaturated polyesters. And epoxy resin.

(Optical adjustment layer)
The optical adjustment layer is a layer for imparting barrier properties to the functional layer 8 by appropriately setting a material to be laminated and a film thickness thereof, and to have predetermined reflection characteristics for obtaining the function and effect described at the beginning. It is.

The material used for the optical adjustment layer 13 is not particularly limited. For example, aluminum oxide, silicon oxide, titanium oxide, magnesium oxide, or a mixture thereof can be used. Among these, it is preferable to use aluminum oxide or silicon oxide from the viewpoint of achieving both reflectivity and barrier properties.
In the present invention, x can take a value of 1 or 2 for silicon oxide SiOx. Similarly, aluminum oxide is not limited to Al ₂ O ₃ .

  Note that the optical adjustment layer 13 may be formed by stacking a plurality of layers having different refractive indexes from those adjacent to each other. For example, inorganic films such as zirconium oxide, aluminum oxide, and titanium oxide, organic films such as zirconium acrylate, hafnium acrylate, and aromatic polymers, or inorganic particles such as titanium oxide, zirconium oxide, and aluminum oxide are dispersed in organic matter. And a high refractive index layer such as an organic film. Examples of the low refractive index layer include inorganic thin films such as silicon oxide and magnesium fluoride, and organic thin films in which hollow structure particles are dispersed in an organic material. These may be laminated alone or in combination, but it is preferable to contain at least one layer of aluminum oxide or silicon oxide from the viewpoint of achieving both reflectivity and barrier properties.

  The thickness of the optical adjustment layer 13 is preferably in the range of 10 nm to 500 nm, and more preferably in the range of 50 nm to 300 nm, from the viewpoint of providing reflectivity while having barrier properties. Here, if the film thickness is less than 10 nm, the film thickness is too thin, so that a uniform film cannot be formed, and a state in which the function as a barrier material cannot be sufficiently achieved is not preferable. On the other hand, if the film thickness exceeds 500 nm, flexibility cannot be maintained in the thin film, and the thin film may be cracked due to external factors such as bending and pulling after the film formation.

(Gas barrier coating layer)
In order to prevent secondary damage in the subsequent process and to provide high barrier properties in combination with the optical adjustment layer 13, a gas barrier coating layer is provided on the opposite side of the optical adjustment layer 13 from the base material layer 12. 14 may be formed.
The gas barrier coating layer 14 includes at least one or more of hydroxyl group-containing polymer compound, metal alkoxide, metal alkoxide hydrolyzate, and metal alkoxide polymer as a component.

  Specific examples of the hydroxyl group-containing polymer compound include water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and starch. The barrier property is most excellent particularly when polyvinyl alcohol is used.

The metal alkoxide is a compound represented by the general formula, M (OR) n (M: metal such as Si, Ti, Al, Zr, R: alkyl group such as CH ₃ and C ₂ H ₅ ). Specific examples include tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ] and triisopropoxyaluminum [Al (O-iso-C ₃ H ₇ ) ₃ ], among which tetraethoxysilane and triisopropoxyaluminum. Is preferable because it is relatively stable in an aqueous solvent after hydrolysis. Examples of the hydrolyzate and polymer include silicic acid (Si (OH) ₄ ) as a tetraethoxysilane hydrolyzate and polymer, and aluminum hydroxide (Al (OH) ₃ ) and the like.

  A catalyst such as tin chloride may be added to the gas barrier coating layer 14 in order to decompose the metal alkoxide. For example, it may be stannous chloride, stannic chloride or a mixture thereof, and may be an anhydride or a hydrate.

  The thickness of the gas barrier coating layer 14 is not particularly limited, but is preferably 10 to 500 nm from the viewpoint of imparting barrier properties.

(Primer layer)
When a primer layer is provided between the substrate and the optical adjustment layer, the optical adjustment layer can be formed uniformly and the barrier property can be improved. In addition, it is preferable to provide a primer layer because adhesion can be stably obtained without being affected by the composition and abundance ratio of the optical adjustment layer.

  As the primer layer, for example, an organic polymer obtained by a two-component reaction of a polyol selected from acrylic polyol, polyvinyl acetal, poly-still polyol, polyurethane polyol, and the like with an isocyanate compound, or a polyisocyanate compound and water Organic compounds having urea bonds, polyethyleneimine or derivatives thereof, polyolefin-based emulsions, polyimides, melamines, phenols, and organic silicas such as organically modified colloidal silica, silane coupling agents and hydrolysates thereof The thing which has a silane compound as a main ingredient is mentioned. In particular, a combination of an acrylic polyol, an isocyanate compound, and a silane coupling agent is preferable. When a primer layer comprising this combination is used, stable and higher adhesion can be obtained between the substrate and the optical adjustment layer.

  The thickness of the primer layer is generally desirably a thickness after drying, and is preferably 5 nm to 500 nm, and more preferably 10 nm to 100 nm. If the thickness is less than 5 nm, it is difficult to obtain a uniform coating film from the viewpoint of coating technology, and conversely, if it exceeds 500 nm, it tends to be uneconomical.

(Relationship between light source and wavelength conversion sheet)
As a combination of the light source 6 and the wavelength conversion sheet 4, for example, a blue light source having a maximum emission wavelength in a range of 400 nm to 500 nm as shown in FIG. 3 and a blue light source shown in FIG. A translucent member including a light emitting material having a maximum emission wavelength in a range of 600 nm can be used.

  Further, the light emitting material included in the wavelength conversion sheet 4 may not be one kind, and light emission having the first maximum emission wavelength in the range of 500 nm to 600 nm excited by the blue light source of FIG. 3 as shown in FIG. A light-transmitting member including a material and a light-emitting material having a second maximum emission wavelength in the range of 550 nm to 650 nm can be used.

Further, the light emission wavelength of the light source 6 may not be in the visible light region of 400 nm to 800 nm. For example, an ultraviolet light source having a maximum light emission wavelength in the range of 300 nm to 400 nm as shown in FIG. 6 and a diagram as shown in FIG. A translucent member containing a light emitting material excited by an ultraviolet light source 6 and having a broad emission wavelength in a visible light region of 400 nm to 800 nm can be used.
Thus, the combination of the light source 6 and the wavelength conversion sheet 4 can be appropriately set according to the application.

(Uneven lens shape)
An uneven shape such as a prism shape, a microlens shape, or a cylindrical shape may be formed on the emission surface side of the wavelength conversion sheet 4. As described above, when the refractive index difference between the particles contained in the wavelength conversion layer and the transparent resin is large, the light emitted from the wavelength conversion sheet becomes emitted light having highly diffusive alignment characteristics. However, by reducing the difference in refractive index between the transparent resin and the dispersed particles, the scattering property by the dispersed particles in the transparent resin is suppressed. Even if the lens shape is formed on the exit surface of the highly scattering sheet, the light condensing effect due to the lens shape is not exhibited. On the other hand, when a lens shape is formed on the exit surface of a sheet having low scattering properties, the light incident on the lens shape surface is emitted as light having orientation characteristics based on the lens shape. By forming the lens shape on the exit surface of the wavelength conversion sheet having a low scattering property, the light condensing effect is enhanced, so that a wavelength conversion sheet having a light condensing property can be obtained.

(Production method)
The wavelength conversion sheet 4 can be manufactured, for example, as follows.
First, the optical adjustment layer 13 is formed on the substrate 12. At this time, when the optical adjustment layer 13 is an inorganic substance, the film is formed using a vapor deposition method or a reactive sputtering method. On the other hand, when the optical adjustment layer 13 is made of an organic material, the film is formed by a coating method such as screen printing.
If necessary, an aqueous solution or water / alcohol mixture containing a water-soluble polymer (hydroxyl-containing polymer compound) and (a) at least one of one or more metal alkoxides and hydrolysates or (b) tin chloride A coating agent mainly composed of a solution is applied onto the surface of the optical adjustment layer 13 to form the gas barrier coating layer 14.

Next, the light emitting material 15a, the transparent resin 15c, the dispersed particles 15b, and a solvent as necessary are mixed to prepare a mixed solution, which is applied to the surface of the functional layer 8 where the optical adjustment layer 13 is not formed. . Here, when the transparent resin 15c is a photosensitive resin, the wavelength conversion sheet 4 of the present embodiment can be obtained by curing the photosensitive resin by UV irradiation (UV curing). The photosensitive resin may be further thermally cured after UV curing. UV curing can be performed at, for example, 100 mJ / cm ² to 1000 mJ / cm ² . Moreover, thermosetting can be performed by heating at 60 to 120 degreeC for 0.1 to 3 minutes, for example. Further, as the transparent resin 15c, a thermosetting resin or a chemically curable resin may be used in addition to the photosensitive resin.
Finally, the other functional layer 13 is laminated from the opposite side so as to sandwich the wavelength conversion layer 15, thereby creating the wavelength conversion sheet 4 that is a translucent wavelength conversion member. The manufacturing method is not limited to this.

  Hereinafter, specific examples and comparative examples of the wavelength conversion sheet according to the present invention will be described. Note that the present invention is not limited to each embodiment.

Example 1
As the functional layer 8a, as shown in FIG. 8A, a polyethylene terephthalate film is 100 μm as the substrate 12a, an aluminum oxide film is 70 nm as the optical adjustment layer 13a on the substrate 12a, and a silicon oxide film is 115 nm thereon. A titanium oxide film is formed thereon by vacuum deposition so as to have a thickness of 70 nm. As shown in FIG. 8B, the spectral reflectance becomes a minimum value of 5% in the wavelength region of 500 nm or less. Thus, a functional layer 8a having a reflectance characteristic in which the spectral reflectance becomes a maximum value of 67% in the wavelength region of 500 nm or more was obtained.
As the functional layer 8b, as shown in FIG. 9A, a polyethylene terephthalate film is 100 μm as the substrate 12b, an aluminum oxide film is 35 nm as the optical adjustment layer 13b on the substrate 12b, and a silicon oxide film is formed thereon. 80 nm, an aluminum oxide film is deposited on it to be 70 nm, and then a silicon oxide film is alternately laminated to a thickness of 80 nm and an aluminum oxide film is 70 nm, and a total of 11 layers are laminated on the substrate by vacuum deposition. By forming the film, as shown in FIG. 9B, the spectral reflectance reaches a maximum value of 50% in the wavelength region of 500 nm or less, and the spectral reflectance reaches a minimum value of 0. 0 in the wavelength region of 500 nm or more. A functional layer 8b having a reflectance characteristic of 5% was obtained.
The wavelength conversion layer 15 adjusts the concentration of CdSe / ZnS 530 (trade name, manufactured by SIGMA-ALDRICH) as quantum dots, and the first maximum emission wavelength in the range of 500 nm to 600 nm shown in FIG. 5 is from 550 nm to 650 nm. A light emitting material 15a having the second maximum emission wavelength in the range, PMMA (polymethylmethacrylate) as the transparent resin 15c, and acrylic particles having a refractive index difference of 0.005 between the dispersed resin 15b and the transparent resin 15c The wavelength conversion layer 15 was obtained by UV-curing the liquid mixture with the above at 600 mJ / cm ² .
The wavelength conversion sheet 4 was obtained by laminating the prepared wavelength conversion layer 15 and the functional layer 8 by UV curing lamination.
As the light source 6, the blue light source having the maximum emission wavelength in the range of 400 nm to 500 nm shown in FIG. 3 was used together with the light guide plate, and the lighting device 3 was created by combining with the obtained wavelength conversion sheet 4.

(Comparative Example 1)
The functional layer 8 consisting only of the base material 12 was laminated on the wavelength conversion layer 15 without providing the optical adjustment layer 13 to obtain the wavelength conversion sheet 4. Other configurations were the same as in Example 1, and the wavelength conversion sheet 4 and the illumination device 3 were created.

<Evaluation of effectiveness of optical adjustment layer>
The light emission distribution of the illumination devices created in Example 1 and Comparative Example 1 was measured, and the effectiveness of the optical adjustment layer was evaluated.

FIG. 10A shows a light emission distribution diagram of Example 1 in which the optical adjustment layer 13 having reflection characteristics corresponding to the light source 6 is formed on the functional layer 8.
In addition, FIG. 10B shows a light emission distribution diagram of Comparative Example 1 in which the optical adjustment layer 13 is not formed on the functional layer 8.

  10A and 10B, it can be confirmed that the emission intensity is increased in the wavelength region of 500 nm or more by providing the functional layer with reflection characteristics. That is, it was confirmed that the incident light from the light source was efficiently converted by the wavelength conversion sheet of the present invention.

(Example 2)
As shown in FIG. 11 (a), a film thickness of a polyethylene terephthalate film as a base material 12a is 100 μm, and a silicon oxide film as an optical adjustment layer 13a is provided on the base material 12a to a thickness of 60 nm by a vacuum vapor deposition method. As a coating layer 14a, a coating liquid containing tetraethoxysilane and polyvinyl alcohol is deposited to 170 nm by a wet coating method, so that as shown in FIG. 11 (b), spectral reflection occurs in a wavelength region of 500 nm or less. A functional layer 8a having a reflectance characteristic in which the reflectance is a minimum value of 6% and the spectral reflectance is a maximum value of 10% in a wavelength region of 500 nm or more is formed.
Also, as shown in FIG. 12 (a), the film thickness of the polyethylene terephthalate film as the base material 12b is 100 μm, and the silicon oxide film is provided as the optical adjustment layer 13b on the base material 12b to a film thickness of 70 nm by a vacuum deposition method. By forming a coating liquid containing tetraethoxysilane and polyvinyl alcohol to 240 nm by a wet coating method as the gas barrier coating layer 14b, as shown in FIG. 12B, in the wavelength region of 500 nm or less, A functional layer 8b having a reflectance characteristic in which the spectral reflectance is a maximum value of 11% and the spectral reflectance is a minimum value of 7% in a wavelength region of 500 nm or more is formed.
Other configurations were the same as in Example 1, and the wavelength conversion sheet 4 and the illumination device 3 were created.

(Example 3)
As shown in FIG. 13 (a), the film thickness of the polyethylene terephthalate film as the substrate 12a is 100 μm, the silicon oxide film is 10 nm as the optical adjustment layer 13a, and tetraethoxysilane and polyvinyl alcohol are included as the gas barrier coating layer 14a. A coating solution is formed to a thickness of 110 nm by a wet coating method, and an optical adjustment layer 13a and a gas barrier coating layer 14a having the same configuration are further laminated one by one, so that the wavelength region is 500 nm as shown in FIG. In the following range, the functional layer 8a having a reflectance characteristic in which the spectral reflectance is a minimum value of 7% and the spectral reflectance is a maximum value of 9.5% in a wavelength region of 500 nm or more is formed.
Further, as shown in FIG. 14 (a), the film thickness of the polyethylene terephthalate film as the substrate 12b is 100 μm, the silicon oxide film is 30 nm as the optical adjustment layer 13b, and tetraethoxysilane and polyvinyl alcohol are used as the gas barrier coating layer 14b. As shown in FIG. 14 (b), a coating liquid containing a film is formed to 120 nm by a wet coating method, and an optical adjustment layer 13b and a gas barrier coating layer 14b having the same configuration are further laminated one by one. In the range of 500 nm or less, the functional layer 8b having a reflectance characteristic in which the spectral reflectance is a maximum value of 11% and the spectral reflectance is a minimum value of 7% in the wavelength region of 500 nm or more is formed.
Other configurations were the same as in Example 1, and the wavelength conversion sheet 4 and the illumination device 3 were created.

(Comparative Example 2)
As for the functional layer 8a, as shown in FIG. 15A, a polyethylene terephthalate film having a thickness of 100 μm as the substrate 12a and a titanium oxide film having a thickness of 230 nm are formed on the optical adjustment layer 13a. ), A functional layer having a reflectance characteristic in which the spectral reflectance is a minimum value of 5% in the wavelength region of 500 nm or less and the spectral reflectance is a maximum value of 32% in the wavelength region of 500 nm or more. 8a was obtained.
As for the functional layer 8b, as shown in FIG. 16A, a polyethylene terephthalate film having a film thickness of 100 μm as the substrate 12b and a titanium oxide film having a thickness of 190 nm in the optical adjustment layer 13b are formed. As shown in b), the reflectance characteristic has a maximum spectral reflectance of 32% in the wavelength region of 500 nm or less and a minimum spectral reflectance of 7% in the wavelength region of 500 nm or more. A functional layer 8b having
Other configurations were the same as in Example 1, and the wavelength conversion sheet 4 and the illumination device 3 were created.

<Appearance evaluation>
The light emitting states of the lighting devices created in Examples 1 to 3 and Comparative Examples 1 and 2 were confirmed, and visual evaluation was performed from the viewpoint of brightness improvement (brightness of surface light emission).

  In the illuminating device using the wavelength conversion sheet of Examples 1 to 3, it was confirmed that the luminance was improved as compared with Comparative Example 1 in which no optical adjustment layer was provided.

  In the lighting device incorporating the wavelength conversion sheet in which only the titanium oxide film is formed on the base material of Comparative Example 2 as in Example 1 to 3, the luminance was improved immediately after light emission, but the barrier property was slightly Due to the inferiority, the luminance decreased with time.

(Comparative Example 3)
Titanium oxide having a refractive index difference from the transparent resin of greater than 0.1 was used for the dispersed particles 15b.
Other configurations were the same as in Example 1, and the wavelength conversion sheet 4 and the illumination device 3 were created.

<Viewing angle characteristics evaluation>

The viewing angle characteristics of the illumination devices created in Example 1 and Comparative Example 3 were measured, and the dispersed particles were evaluated.

FIG. 17A shows the measurement results when the refractive index difference between the transparent resin 15c and the dispersed particles 15b created in Example 1 is 0.005.
Moreover, the measurement result in the case where the refractive index difference of the transparent resin 15c and the dispersed particles 15b created in Comparative Example 3 is larger than 0.1 is shown in FIG.

  17 (a) and 17 (b), it can be confirmed that the condensed light can be emitted without diffusing by using dispersed particles having a small difference in refractive index from the transparent resin.

  In the description of each of the embodiments and the modifications described above, an example in which the illumination device 3 is used in the liquid crystal display device 1 has been described. However, the illumination device 3 is not applied only to the liquid crystal display device 1. For example, it can be used as a lighting device for a display device other than a liquid crystal display device such as a signboard or an electronic book. Further, it is not essential to combine with a display device, and for example, it can be used as a single lighting device.

  In the description of each of the above embodiments and modifications, the example in the case where the diffusion sheet 28 and the light collecting sheet 20 are provided between the wavelength conversion sheet 4 and the light guide has been described. The configuration of is also possible. For example, the light collecting sheet 20 can be used instead of the diffusion sheet 28.

  In the description of each of the embodiments and the modification examples described above, the functional layer 8 includes the gas barrier coating layer 14 and the optical adjustment layer 13. However, this is an example, and the functional layer 8 has other functions. You may provide the layer which has. For example, a hard coat layer or a conductive film can be formed on the outermost surface.

  In the description of the above embodiment, an example in which the backlight is arranged in an edge light type backlight has been described. However, as shown in FIG. 18, a direct type backlight may be used, and as shown in FIG. You may stick together and use for the illuminating device which emits surface light like EL.

  All the constituent elements described above can be implemented by appropriately changing or deleting combinations within the scope of the technical idea of the present invention.

1 Liquid crystal display device (display device)
2 Image display element 3 Illumination device 4 Wavelength conversion sheet 5 Reflector (reflective member)
6 Light source 7 Light guide 8 Functional layer 9 Liquid crystal layer 10, 11 Polarizing plate 12 Base material 13 Optical adjustment layer 14 Gas barrier coating layer 15 Wavelength conversion layer 15a Light emitting material 15b Dispersed particles 15c Transparent resin 18 Light deflection element 20 Light collecting sheet 23 Base material 24 Prism 28 Diffusion sheet H51 High refractive index layer H61 Low refractive index layer H71, H72 High refractive index layers H81, H82, H83, H84, H85, H86 High refractive index layers L81, L82, L83, L84, L85 Low Refractive index layer H91, H92 High refractive index layer L91, L92 Low refractive index layer

Claims (9)

A wavelength conversion sheet having a wavelength conversion layer and a light incident surface and a light emission surface arranged to face each other in a positional relationship across the wavelength conversion layer,
The wavelength conversion layer contains at least one kind of light emitting material that converts the wavelength of incident light to the long wavelength side,
On the light incident surface, a first base layer formed on the wavelength conversion layer side, and a first functional layer in which at least a first optical adjustment layer is laminated on the first base layer With
The first optical adjustment layer has a layer made of at least silicon oxide or aluminum oxide,
The spectral reflectance on the surface of the first optical adjustment layer opposite to the first base material layer has a minimum value of 0.5% to 10% in the wavelength region of 300 nm to 500 nm. A wavelength conversion sheet characterized by that. A wavelength conversion sheet having a wavelength conversion layer and a light incident surface and a light emission surface arranged to face each other in a positional relationship across the wavelength conversion layer,
The wavelength conversion layer contains at least one kind of light emitting material that converts the wavelength of incident light to the long wavelength side,
A second functional layer in which at least a second optical adjustment layer is laminated on the second base material layer and the second base material layer formed on the wavelength conversion layer side on the light emitting surface. With
The second optical adjustment layer is
Having a layer of at least silicon oxide or aluminum oxide;
A wavelength conversion sheet, wherein a maximum value of spectral reflectance in a wavelength region of 300 nm to 500 nm is higher than a minimum value of spectral reflectance in a wavelength region of 500 nm to 680 nm.   The refractive index difference between the translucent resin constituting the wavelength conversion layer and the dispersed particles contained in the translucent resin is 0.1 or less, according to claim 1 or 2. Wavelength conversion sheet. The first optical adjustment layer and the second optical adjustment layer are:
The layer having a refractive index different from that of an adjacent layer among any one of an inorganic material, an organic material, and a mixture of an inorganic material and an organic material is laminated in addition to the layer made of silicon oxide or aluminum oxide. The wavelength conversion sheet according to any one of 1 to 3. It is an illuminating device using the wavelength conversion sheet of any one of Claims 1 thru | or 4, Comprising:
The light emitted from the light source is incident from the light incident surface side of the wavelength conversion sheet.   The illumination device according to claim 5, wherein a maximum emission wavelength of the light source exists in a wavelength region of 300 nm to 500 nm.   The illumination device according to claim 5 or 6, wherein the wavelength width of the light emission distribution when the maximum value of the light emission intensity of the light emitted from the light source is halved is in the range of 10 nm to 60 nm.   A display device comprising the illumination device according to claim 5, wherein a display panel and a color filter for displaying an image are arranged on an observer side of the wavelength conversion sheet. .   The display device according to claim 8, wherein an optical sheet on which either a prism shape or a microlens shape is formed is laminated on a light exit surface side of the wavelength conversion sheet.

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